class Solution7 {

    int ret;
    boolean[] check;

    public int countArrangement(int n) {
        check = new boolean[n + 1];

        dfs(1, n);
        return ret;
    }

    public void dfs(int pos, int n){
        if(pos == n + 1){
            ret++;
            return ;
        }

        for(int i = 1; i <= n; i++){
            if(check[i] == false && (i % pos == 0 || pos % i == 0)){
                check[i] = true;
                dfs(pos + 1, n);
                check[i] = false;
            }
        }
    }
}